ipvs: Kconfig cleanup

IP_VS_PROTO_AH_ESP should be set iff either of IP_VS_PROTO_{AH,ESP} is
selected. Express this with standard kconfig syntax.

Signed-off-by: Michal Marek <mmarek@suse.cz>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>